1. Field of the Invention
The invention relates generally to systems for delivering agricultural chemicals, to crop fields. More specifically, the invention pertains to a delivery system for both pesticide products and crop yield enhancement materials, employing water-dispersible extruded granules, manufactured from a uniformly blended composition of at least one active chemical ingredient, a solid carrier, and a binder.
2. Description of the Prior Art
A wide range of agricultural chemicals has been developed to increase agricultural production. Some of these chemicals, generally designated pesticides, are designed to eliminate competing plant growth or parasitic organisms. Consequently, the term pesticide includes a variety of products such as herbicides, insecticides, and fungicides. Another group of products, which is non-pesticidal in nature, is designed to maximize crop yields by acting directly on the crop itself. These non-pesticidal materials include, for example, plant growth regulators, insect growth regulators, micronutrients, and fertilizers.
Agricultural chemical products have been formulated as emulsifiable concentrates, wettable powders, dusts, water dispersible granules, baits, water soluble concentrates, water or oil based suspensions, and impregnated or extruded granules. These chemical products have been delivered to the target site using either ground or aerial equipment, specially adapted to handle the various product forms. For example, spraying equipment is used to deliver both water based dilute and concentrate sprays of active ingredients. Dry application of active ingredients in the form of dusts, baits, and granular products is also employed. And, chemigation, drip-line, and wick application techniques are commonly employed in the industry as well.
The primary, beneficial effects of these agricultural chemicals are sometimes accompanied by secondary effects that detrimentally impact the environment surrounding the crop field. Within that surrounding environment are humans, animals, water, and non-target plants. Secondary effects on the environment increase as the result of: (1) off-target drift of the applied product; and, (2) volatilization of the active chemical ingredient from the applied product.
Off-target drift refers to the tendency of air-borne particles or droplets of product to be carried by wind and air currents off the application site, before settling on the ground or becoming adhered to plant material. Typically, this occurs during the application process itself, but it may also occur after application, if the chemical product is susceptible to being blown off the ground or plant material.
Volatilization of the active ingredient of the product results in the the unwanted airborne transport of vaporized forms of chemicals to adjacent lands, where it may adversely affect humans, animals, and off-target plant materials. Volatilization also necessarily reduces the efficacy of the chemicals applied on the target property, as a portion is lost and applied where it is not intended.
Ground application of chemicals, whether in a spray form or in a dry form, is vulnerable to off-target drift and volatilization. Aerial application, while capable of covering large crop areas relatively quickly, is even more vulnerable to drift and volatilization problems. Owing to the speed and elevation of the plane, and the unpredictability of wind and air currents especially around the margins of the target areas, the chances for unwanted secondary application of chemicals are enhanced by aerial application.
Efforts have been made to reduce drift by increasing droplet size, and to reduce volatalization by encapsulating droplets. The product chemistry of the active ingredients sought to be applied also limit the options on the type of product formulation and the manner of application. For example, the prior art teaches a method of liquid encapsulation of the active ingredient in a plastic or a polymer. U.S. Pat. No. 4,405,357, discloses a liquid encapsulation formulation of an active ingredient, sold under the trademark CLOMAZONE. Liquid encapsulation maintains the active ingredient in relatively large droplet form, reducing air-borne drift. In addition, the plastic or polymer outer coating effectively seals off the active ingredient, thereby reducing volatilization and its detrimental effects.
It would be theoretically advantageous to so encapsulate all of the active ingredients in agricultural chemicals, but drawbacks remain. First, the product chemistry of the active ingredients sought to be applied may limit the options on the type of product formulation and the manner of application. Certain active ingredients, individually or in combination with others, are not as suitable for liquid encapsulation as others. Thus, if two or more active ingredients are combined, liquid encapsulation may not reduce the volatilization of the active ingredients as effectively, as with a single active ingredient. An example of this interaction between two active ingredients is the combination of CLOMAZONE and a fertilizer. The fertilizer is a humectant, absorbing water out of the air, thereby increasing the volatility of the CLOMAZONE to the extent that liquid encapsulation is not very effective. Second, liquid encapsulation is quite expensive, so the cost/benefit analysis does not always favor liquid encapsulation as a desired product formulation.
It has been determined that water-dispersible, extruded granules, containing active chemical ingredients, provide an effective delivery system for both pesticide products and crop-yield enhancement materials. The extruded granules are manufactured from a composition including at least one active chemical ingredient, a solid carrier, and a binder. The active ingredients may be selected from one or more pesticide products, either alone or in combination with a crop-yield enhancing product. The active ingredients may be micro-encapsulated with a plastic or polymer coating, but such micro-encapsulation of the active ingredients is not necessary to practice the invention.
To form the composition, one or more of the active ingredients is first blended uniformly with a solid carrier. The solid carrier is selected from an approved list of xe2x80x9cinert ingredientsxe2x80x9d which can be applied safely with pesticides. The blended composition is then extruded through a die to form small granules of generally uniform size.
The extruded granules are next coated with a liquid solution of an adhesive binder, such as a lignosulfonate material. The binder helps maintain the solid carrier together, and also reduces attrition, or dust-producing abrasive chaffing between the granules. Optionally, a dispersant may be added to the adhesive binder solution. The dispersant assists in the physical disintegration of the granule, and the desirable equal distribution of the inert ingredient, when the granules are immersed in water. Finally, the solution-coated granules are de-hydrated to a moisture content within the range of 1-10%, and preferably about 5%-6%. Then, the extruded granules are ready for use.
The granules are well suited for aerial application to crop fields. They are dry, easy to handle, and do not produce attrition dust. Owing to their relatively high density, the extruded granules fall rapidly, and are not influenced or affected by minor wind currents. Also, the dense granules sink rapidly after they fall into the water, and disintegrate in the water to spread the active ingredient quickly.